Two-stage catalytic hydrogen processing of a lube oil



United States Patent G 3,494,854 TWO-STAGE CATALYTIC HYDROGEN PROCESSINGOF A LUBE OIL James P. Gallagher, Park Forest, and Maurice K. Rausch,Homewood, 11]., assignors to Sinclair Research, Inc., New York, N.Y., acorporation of Delaware N Drawing. Filed Apr. 1, 1968, Ser. No. 717,918Int. Cl. Cg 37/02, 13/02, 41/02 US. Cl. 20859 10 Claims ABSTRACT OF THEDISCLOSURE Lubricating oil of reduced pour point is prepared withoutmaterially decreasing the flashpoint for a given viscosity level bycontacting a mineral oil with hydrogen in a first step in the presenceof a sulfur-resistant catalyst (e.g., nickel molybdate on alumina) undermoderate conditions and further contacting in a second step withhydrogen in the presence of a calcium-exchanged, crystallinealuminosilicate catalyst containing a platinum group metal to effect amore severe treatment of the oil.

This invention relates to a process employing two distinct catalysttypes in separate treating zones to produce high quality lubricating oilstocks from raw, heavy mineral lubricating oil distillates. Moreparticularly, this invention concerns a hydroisomerization-hydrocrackingcatalytic conversion process for the production of refined minerallubricating oils having substantially reduced pour points withoutsubstantial reduction of flash point for a given viscosity oil.

Many of the present day refining techniques employed to produce highquality lubricating oils having low pour points possess certainundesirable features. For example, dewaxing methods for reducing thepour point of raw lubricating oil distillates, such as solvent dewaxing,have high refrigeration requirements and low filter rates, resulting inhigh process costs. Other techniques, such aS urea adduction encountergreat difiiculties in continuous operations due to handling and pluggingproblems. Catalytic processes are known which produce low pour pointpetroleum stocks; however, the' products of such processes to datelikewise possess extremely low flash points (e.g., below 225 P.) whichis undesirable.

The present invention concerns a two-stagehydroisomerization-hydrocracking process wherein a raw, heavylubricating oil derived by distillation from a waxy mineral crude oilhaving a high pour point, e.g. for instance, at least about 50 F., isconverted into refined mineral lubricating oil of substantially reducedpour point, Without substantially reducing the flash point for a givenviscosity level. According to the process of the present invention araw, heavy lubricating oil distillate is contacted in a first stage withhydrogen in the presence of a sulfurresistant,desulfurization-denitrogenation or hydrogenation-type catalyst undermoderate or hydrotreating conditions. The hydrotreated oil from thefirst stage, if desired after stripping to remove materials boilingbelow the lubricating oil range is further contacted in a second stagewith hydrogen in the presence of a platinum group metalcontaininghydroisomerization-hydrocracking catalyst of special composition toeffect a more severe treatment of the oil. The efiiuent from the secondstage may be fed, for instance, to a stream stripper to remove excessivehydrocracked components boiling below the lube oil range, and thefinished mineral lubricating oil having a reduced pour point, forexample, of about 25 to +25 F., recovered.

The mineral lubricating oil distillates treated by the process of thepresent invention are essentially raw, heavy "ice lubricating oildistillates, for instance, a lubricating oil fraction obtained by thevacuum distillation of a Waxy mineral crude oil. These lubricating oilfeedstocks often possess a viscosity in the range of about 35 to SUS at210 F., and a pour point of at least about 50 F., frequently at leastabout 70 F.

The hydrogen treatment in the first stage of the present process isconducted at temperatures of about 600 to 800 F., preferably about 650to 750 F. The other reaction conditions generally include pressures ofabout 1000 to 4000 p.s.i.g., preferably about 1000 to 2500 p.s.i.g.;weight hourly space velocities (WHSV) of about 0.1 to 1, preferablyabout 0.2 to 0.5; and molecular hydrogen to feed oil ratios of about 500to 5000 s.c.f./b., preferably about 1000 to 2500 s.c.f./b.

The hydrogenated oil from the first hydrogenation stage preferably afterstripping, is subjected to a second, more severe hydrogenationoperation. The catalyst in the second reactor is especially chosen toeffect hydroisomerization and hydrocracking. Temperatures in the secondstage range from about 850 to 1000 F., with temperatures of about 900 to975 F. being preferred. Other reaction conditions often includepressures of about 300 to 2000 p.s.i.g., preferably about 400 to 1000p.s.i.g., weight hourly space velocities of about 0.25 to 2, preferablyabout 0.3 to 0.5, and molecular hydrogen to feed oil ratios of about1000 to 10,000 preferably about 2000 to 6000, s.c.f./b.

The desulfurization-denitrogenation type catalysts used in the firststage of the present process can be any of the sulfur-resistant orsulfur-active, non-precious metal hydrogenation catalysts, such as thoseconventionally employed in the hydrogenation of heavy mineral oils.Examples of suitable catalytic ingredients are tin, vanadium, members ofGroup VIB in the Periodic Table, i.e., chromium, molybdenum andtungsten, and metals of the iron group, i.e., iron, cobalt and nickel.These metals are present in catalytically effective amounts forinstance, about 2 to 30 weight percent and may be present in theelemental form or in the form of oxides or sulfides, the sulfide formbeing the preferred form. Mixtures of these materials or compounds oftwo or more of the oxides or sulfides can be employed, for example,mixtures or compounds of the iron group metal oxides or sulfides withthe oxides or sulfides of Group VI-B constitute very satisfactorycatalysts. Examples of such mixtures or compounds are nickel molybdate,tungstate or chromate (or thiomolybdate, thio-tungstate or thiochromate)or mixtures of nickel or cobalt oxides with molybdenum, tungsten orchromium oxides. As the art is aware and as the specific examples belowillustrate, these catalytic ingredients are generally employed whiledisposed on a suitable carrier of the solid metal oxide type, e.g., apredominantly calcined or activated alumina. Commonly employed catalystshave about 1 to 10% of an iron group metal and 5 to 25% of a Group VI-Bmetal (calculated as the oxide). Advantageously, the catalyst issulfided nickel-molybdena supported on alumina. Such preferred catalystscan be prepared by the method described in US. Patent 2,938,002.

The platinum group metal-containing hydroisomerization-hydrocrackingcatalyst used in the second state of the present invention, unlike thecatalyst employed in the first stage, is not normally sulfur-resistantand contains a major amount of a calcium-exchanged crystallinealuminosilicate having pores of about 8 to 14 angstrom units in size anda silica-to-alumina mole ratio of about 2 to 3:1; and a minor catalyticamount, say about 0.1 to 5, prefera'bly about 0.3 to 2 weight percent ofa platinum group metal. If desired, a minor amount, for instance about 5to 20 or more weight percent of other suitable carrier materials, forexample a solid metal oxide, such as silica, silica-alumina, clay etc.may be added to the second stage catalyst composition.

The crystalline aluminosilicate component of the second stage catalystmay be synthetic or naturally-occurring and has a pore size of about 8to 14 A., preferably about 9 to 13 A. Usually, with a given material,the pores are relatively uniform in size, and the silica-to-alumina moleratio is about 2 to 3:1. The aluminosilicate is at least about 50%,preferably at least about 70%, calcium-exchanged. That is, at leastabout 50% to the cations present in the aluminosilicate are replaced bycalcium. Calcium exchange is commonly carried out by exchange of thecations of the synthetic or naturally-occurring aluminosilicates withcalcium ions, for instance thrOugh contact with an aqueous solution ofcalcium chloride and subsequently calcining the aluminosilicate, forinstance at a temperature of about 500 to 1500 F. preferably about 700to 1100 F.

The platinum group metals of the second stage catalyst include suchGroup VIII metals as, for example, platinum, palladium, rhodium oriridium. The platinum group metal may be present in the metallic form oras a sulfide, oxide or other combined form. The metal may interact withother constituents of the catalysts, but if during use the platinumgroup metal is present in the metallic form, then it is preferred thatit be so finely divided that it is not detectable by X-ray diffractionmeans, i.e., that it exists as crystallites of less than about 50 A. insize. The platinum group metal may be added before or after thecalcination of the calcium-exchanged crystalline aluminosilicate, by,for example, ion exchange or impregnation. In any event, after theplatinum group metal is added, the catalyst is dehydrataed and activatedat the calcination temperature described above.

An available method for adding the platinum group metal by ion exchangecomprises treating the crystalline aluminosilicate with an aqueoussolution containing complex water-soluble, metal-amine cations, bothorganic and inorganic, of the metal to be deposited in the crystalstructure. These complex cations ion-exchange with the cations presentin the crystalline aluminosilicate. The exchanged material is thenremoved from the solution, dried and activated or calcined, for example,by heating the material to a temperature of about 500 F. in a flowingstream of inert dry gas or vacuum. The activation may be eifected at atemperature below the temperature at which the complex cations aredestroyed. The activated material may then be subjected to heattreatment to a temperature not exceeding about 1200 F. and preferablynot exceeding about 925 F. in vacuum or inert atmosphere whereby thecomplex cation is destroyed and the metal is reduced in the material.Should the thermal treatment be insufiicient to reduce the metal of thecomplex cations to the elemental state, chemical reduction either aloneor in combination with thermal reduction may be employed. Through theoperation excessive temperatures and extremes of acidity are to beavoided since they may tend to destroy the crystal structure of thecrystalline aluminosilicate.

The platinum group metal may also be added by impregnation. Thecrystalline aluminosilicate, either with or without previous evacuationcan be soaked in either a dilute or concentrated solution, usuallyaqueous chloroplatinic acid, ammonium hexathio-cyanoplatinate (IV) orhexathiocyanate platinic acid, often in an amount just sufficient to wetthe material and be completely absorbed.

The catalysts of either stage of the process of this invention can, ifdesired, be formed into macrosized particles by tabletting or extruding.Generally, these particles are about to /2" in diameter and about to 1"or more in length. Although these macrosized particles are usuallyformed after dehydration and before calcination, this, of course, isoptional and can be done at any t me f und most o ve ient.

The process of the present invention is illustrated by the followingexample which is not to be considered as limiting.

EXAMPLE I A waxyraw, mixed base lubricating oil distillate having theproperties of the feedstock in Table I, below, was contacted withhydrogen in the presence of a calcined nickel-molybdena on aluminacatalyst at a temperature of 700 F., a pressure of 1500 p.s.i.g., aweight hourly space velocity of 0.25 and a hydrogen rate of 1500 s.c.f./b. of oil. The catalyst, which contained 2.3 percent nickel and 15.6percent molybdenum as oxides supported on activated alumina waspretreated with hydrogen sulfide at 350 F. for two hours using ones.c.f.-H S/hr./ grams of catalyst. The hydrocarbon product from thisfirst stage was flashed to remove light gaseous products and furthertreated in a second stage at a temperature of 950 F., a pressure of 500p.s.i.g., a weight hourly space velocity of 0.35 and a hydrogen rate of5000 s.c.f./b. of feed in the presence of a calcinedplatinum-containing, crystalline aluminosilicate extrudate catalyst. Thecatalyst contained about 0.8% platinum supported on a carrier which wascomposed of a calcium-exchanged, crystalline sodium alluminosilicatehaving a pore size of about 10 A. and a silica-to-alumina mole ratio ofabout 2.5 :1 and about 15 weight percent clay which was added as abinder prior to extrusion. The catalyst analyzed 0.766% platinum 8.55%calcium and 1.57% sodium. The effluent product from the second stage Wassteam stripped to remove lighter hydrocarbon components. The propertiesof the feedstock compared to that of the first stage and final productsare as follows:

These data illustrate the major reduction in pour point of the secondstage product resulting from the process of this invention. The productfrom the first stage reactor (Oil B) may be seen to have undergonesubstantial hydrocracking but no reduction in pour point, while theproduct from the second stage reactor (Oil C), following steam strippingto remove lighter hydrocarbon components, has a pour point of 0 FL, downfrom the pour point of the feedstock.

It is claimed:

1. A process of producing a hydrocarbon lubricating oil having a reducedpour point without a materially decreased flashpoint for a givenviscosity level, which comprises contacting a raw, mineral lubricatingoil distillate from a waxy mineral crude oil having a pour point of atleast about 50 F., with hydrogen in the presence of a sulfur-resistanthydrogenation catalyst at a temperature of about 600 to 800 F. andfurther contacting the resulting hydrogenated oil hydrogen in thepresence of a hydroisomerization-hydrocracking catalyst at a temperatureof about 850 to 1 000" F., said hydroisomerizationhydrocracking catalystcomprising a major amount of an at least 50% calcium-exchangedcrystalline aluminosilicate having a pore size of about 8 to 14 A, and asilica-to-alumina mole ratio of about 2 to 3:1 and a minor, catalyticamount of a platinum group metal.

2. The process of claim 1 wherein said crystallinealuminosilicate is atleast 70% calcium exchanged.

3. The process of claim 2 wherein the contact of said raw minerallubricating oil distillate with hydrogen is conducted at a pressure ofabout 1000 to 4000 p.s.i.g., a weight hourly space velocity of about 0.1to 1 and a hydrogen feed rate of about 500 to 5000 s.c.f./b.

4. The process of claim 3 wherein the contact of said hydrogenated oilwith hydrogen is conducted at a pressure of about 300 to 2000 p.s.i.g.,a weight hourly space velocity of about 0.25 to 2 and a hydrogen feedrate of about 1000 to 10,000 s.c.f./b.

5. The process of claim 4 wherein the mineral lubricating oil distillatehas a viscosity of about 35 to 90 SUS at 210 F. and a pour point of atleast about 70 F.

6. The process of claim 5 wherein the sulfur-resistant catalyst containsmolybdenum and an iron group metal.

7. The process of claim 6 wherein the iron group metal is nickel.

8. The process of claim 5 wherein the platinum group metal is platinum.

9. The process of claim 8 wherein the contact of said raw minerallubricating oil distillate with hydrogen is conducted at a temperatureof about 650 to 750 F., a pressure of about 1000 to 2500 p.s.i.g., aWeight hourly space velocity of about 0.2 to 0.5 and a hydrogen feedrate of about 1000 to 2500 s.c.f./b. and the resulting hydrogenated oilis further contacted with hydrogen at a temperature of about 900 to 975F a pressure of about 400 to 1000 p.s.i.g., a weight hourly spacevelocity of about 0.3 to 0.5 and a hydrogen feed rate of about 2000 to6000 s.c.f./b.

10. The process of claim 9 wherein the sulfur-resistant catalystcontains molybdenum and nickel.

References Cited UNITED STATES PATENTS 3,308,055 3/1967 Kozlowski a20818 3,365,390 1/1968 Egan et a1. 208-18 3,385,781 5/1968 Hamner et al20859 3,431,194 3/1969 Bartok et a1. 208-89 3,431,198 3/1969 Rausch208-143 HERBERT LEVINE, Primary Examiner US. Cl. X.R.

